Methods and apparatus for expanding the usefulness of hand tools by affixing alternate types of tool heads to a single tool handle have been the subject of much inventive effort over the years. The basic approach of providing multipurpose tools flows naturally from the need to apply a number of different tool heads to a workpiece--or to garden soil--serially in time. In gardening or agricultural uses, a first tool type might be used to precondition the soil, and a second tool type might occasionally be needed to rework particular areas, or to complete processes which were missed on the initial passes. The use of a long-handled hoe followed by the use of a long-handled rake to collect the debris produced by the hoe gives an example of where iterative uses of alternate tool types are commonly needed. Hence, multipurpose tools of wide varieties abound; as do devices where a number of different tool heads may be affixed to a single, specially adapted handle.
Descriptions of typical prior art approaches may be found in a number of U.S. Patents. Illustrative teachings of multipurpose gardening tools are disclosed in U.S. Pat. No. 2,793,904 to Govan, Jr., U.S. Pat. No. 4,606,089 to King, and as early as 1893 in U.S. Pat. No. 510,326 to Carman. In the 1986 King patent, there is shown an arrangement where up to five different tool heads are carried by a single, special-purpose handle, with the one desired tool head type rotated into working position from a collection of nested tool heads. The Govan, Jr., patent teaches the affixing of any one of a variety of tool head types--one at a time--to a tool handle using a spring-loaded hook and loop retaining device. The early patent to Carman teaches a simpler approach wherein tool heads are inserted into a longitudinally apertured tool handle and retained by means of a transversely positioned nut and bolt. Various types of interconnecting or quick-acting fastening means are also taught in prior U.S. Patents; with U.S. Pat. No. 2,527,256 to Jackson and U.S. Pat. No. 4,586,399 to Kassai being illustrative of round bayonet-type interconnectors and square, latch-retained interconnections respectively.
While each of these prior art approaches appears to address a particular well known need, each incorporates diverse levels of practicality both in initial fabrication as well as in subsequent usage. Therefore, there is a clear need for an improved approach to providing tool expansion methods and apparatus, and particularly for an approach where a preexisting standard tool serves as the basic unit to which alternate tool head types may be added.